Getting His Digestive System On Track


digestive system

Good nutrition is only healthful if your horse’s digestive system is working properly.

Your horse can eat the best diet possible, but if his digestion is faulty, it won’t do him a lot of good. Digestion is the process of breaking down the carbohydrates, fiber, fat and protein in foods into their basic structural units so they can be absorbed. Horses evolved to process high fiber grasses and to browse, not to eat grains or other concentrated feeds. To process the latter successfully requires a well-coordinated interplay involving the horse’s own digestive enzymes and the microbes living in the intestinal tract.

Digestive Enzymes

Horses digest their food using both the digestive enzymes their bodies produce, and the organisms in their intestinal tracts that break down the food. The digestion of sugars, starch and other complex plant carbohydrates actually starts in the upper portion of the stomach where bacteria (Lactobacilli) begin the process. In the small intestine, both bacteria and digestive enzymes continue this process.

Digestive enzymes from the pancreas are responsible for breaking down dietary fats into fatty acids; proteins to amino acids; starches to glucose; and simple disaccharides (two sugars bonded together) into their monosaccharide form. This has to occur before your horse’s food can be absorbed. The microorganisms in his large intestine also ferment the remaining forms of complex plant carbohydrate/fiber into ultra short chain fatty acids that are absorbed and used as nutrients.

The absorption of amino acids, sugars and fats can only occur in the small intestine, the upper portion of the horse’s digestive tract. Food is broken down into a simpler form by a digestive enzyme from the stomach, along with several others in the small intestine. Since the food only remains in the stomach and small intestine for a total of about six hours, it’s important that the digestive enzymes are operating efficiently.

Cellulase, hemicellulase, phytase, betaglucanase and pectinase are enzymes that break down the fiber fractions of the diet. These are normally produced by the bacteria and protozoa in the cecum and colon. They can benefit horses with poor populations of microorganisms, and complement the use of pre or probiotics in those horses.

Ingredients in Digestive Supplements

Digestive supplements may contain one or more pure isolated digestive enzymes. These enzymes have specific activities in the digestion of starch/sugars, fiber, protein or fat. Feeding these purified enzymes decreases the work that the horse’s own pancreatic enzymes and microorganisms have to do.

Probiotics are live organisms, bacteria or fungi. An important group is the lactic acid producers, which include Lactobacilli, Enterococci and Bifidobacteria. Lactic acid bacteria colonize the stomach and upper portion of the digestive tract (the small intestine) where they assist the horse’s pancreatic enzymes in breaking down starch and sugars. These organisms ferment them to lactic acid. After being absorbed, the lactic acid can be metabolized or converted into glucose inside the horse’s body.

It’s important that the digestion of starch and sugars in the small intestine be as complete as possible. If too much makes its way back to the cecum and large intestine, high levels of lactic acid can cause a drop in pH. This interferes with fiber fermentation, and gives possible symptoms of bloating, diarrhea or excess fluid passed along with formed manure. If severe enough, the intestinal lining can be damaged.

Other organisms assist in maintaining the normal pH of the hind gut, including Propionibacteria, and the yeasts Aspergillus and Saccharomyces cerevisiae. This in turn improves the fermentation of fiber fractions in the hind gut. Keeping the various populations of organisms in a healthy balance also decreases the risk of harmful organism overgrowth by gently stimulating the immune system and secreting antimicrobial substances.

Fermentation products are solids extracted from the fluid cultures of various organisms. Substances secreted by the organisms include their fermentation by-products, antimicrobial substances, and growth factors. Fermentation products are also rich sources of digestive enzymes and metabolic intermediates that are of use to the organisms.

Because of the complexity of the digestive process and the horse’s limited ability to handle starch, problems related to digestive upset are common. Supporting this process with a combination of digestive enzymes, beneficial probiotics and microbial fermentation products can maximize his digestive efficiency.

When Enzyme Supplementation Can Help

• The horse has trouble holding weight, even if on a probiotic. Older horses with no obvious dental issues may experience inefficient chewing caused by changes in the angle of their chewing surface related to wear and dental work. In other species, digestive efficiency and enzyme levels can also decline with age, and the same may be true for the horse.

• The horse is recovering from pancreatitis. Pancreatitis is rarely diagnosed because pancreatic enzymes are not included on routine chemistry screens. However, it does happen, both as a primary problem and as related to inflammation or ulceration in the small intestine. Since the pancreas is the organ that secretes digestive enzymes, supplementation during the recovery phase may be helpful.

• The horse has had surgery that removes a section of small intestine. This decreases the time food spends in the small intestine, and also the surface area available for absorption. Increasing the enzyme activity can help speed food breakdown so more nutrients are absorbed.

• The horse requires grain to hold his weight but has problems with bloating and soft manure when fed grain. These symptoms indicate that starch/sugars (or to a lesser extent, protein or fat) are not being well digested and absorbed in the small intestine.

• The horse struggles to maintain normal weight despite a high intake of food, though he is otherwise healthy.

• The horse needs help adapting to a new diet.


Eleanor Kellon, VMD, currently serves as the Staff Veterinary Specialist for Uckele Health & Nutrition. An established authority in the field of equine nutrition for over 30 years, Dr. Kellon is a valuable resource in the field of applications and nutraceuticals in horses. She formerly served as Veterinary Editor for Horse Journal and John Lyons Perfect Horse and is the owner of Equine Nutritional Solutions, a thriving private practice. A prolific writer, Dr. Kellon is the author of many best-selling books on a variety of medical and nutritional topics and has contributed to both lay and professional publications.
Founded in 1962, Uckele Health & Nutrition has been a trusted leader in the formulation, development and manufacture of quality nutritional supplements for 50 years. With leading edge experience in nutritional research and science, the Uckele team manufactures quality formulas from concept to shelf, formulating a vast array of high potency, balanced nutritional supplements to support optimal health and performance at the highest level.
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